High strength zinc alloys

ABSTRACT

Zinc alloys having improved physical properties consist essentially of 10 to 30 percent by weight of aluminum, 0.3 to 10 percent by weight of copper, 0.01 to 0.1 percent by weight of magnesium, 0.005 to 0.3 percent by weight of at least one of the metals calcium, lithium and sodium, and the balance zinc.

United States Patent 1191 Balliett Nov. 26, 1974 [54] HIGH STRENGTH ZINC ALLOYS 7 3,734,785 5/1973 Watson et al. 75/178 AM [75] Inventor: Robert Wayne Balliett, Beaver Falls, FOREIGN PATENTS OR APPLICATIONS 663,274 8/1938 Germany 75/178 AM [73 Assignee; St. Joe Minerals Corporation, New 703,977 3/1941 Germany 75/178 AM York, NY. Primary Examiner-L. Dewayne Rutledge [22] Flled' May 1973 Assistant ExaminerE. L. Weise [21] Appl. No.: 358,275 Attorney, Agent, or Firm-Cameron, Kerkam, Sutton,

Stowell '& Stowell [52] US. Cl. 75/178 AM [51] Int. Cl. C22c 17/00 [57] ABSTRACT [58] held of Search 75/178 178 178 AC Zinc alloys having improved physical properties consist essentially of 10 to 30 percent by weight of alumi- [56] References cued num, 0.3 to 10 percent by weight of copper, 0.01 to UNITED STATES PATENTS 0.1 percent by weight of magnesium, 0.005 to 0.3 perl,945.288 l/l934 Morell 75/178 AM cent by weight of at least one of the metals calcium, 2,102,8 9 12/1937 Winter 75/178 A lithium and sodium, and the balance zinc. 3,527,601 9/1970 Foerster 75/178 A 3,676,115 7/1972 Hare et a1 75/178 AM 4 Claims, N0 Drawings HIGH STRENGTH ZINC ALLOYS it has been known for over twenty-five years that near-eutectoid alloys of zinc and aluminum upon suitable heat treatment acquire the capacity for a high degree of plastic extension which has'been termed superplasticity. A review of theliterature in the field of aluminum-zinc superplastic alloys is provided by an article entitled Superplasticity in an Al-Zn Alloy by W. A. Backofen et al. in Transactions ofthe ASM, Vol. 57, 1964, pages 980-990.

U.S. Pat. No. 1,945,288 to Morell disclosed eutectoid alloys of zinc and aluminum containing minor proportions of magnesium and copper. Although the Morell patent did not explicitly describe the phenomenon of superplasticity, it became very obvious from the literature in this field cited and discussed in the Backofen article referred to above that the alloys described in the Morell patent possessed the property of superplasticity.

It has now been found that alloys of improved physical properties including high ultimate tensile strengths at ambient temperatures, improved stress rupture lives, and high creep strengths as well as potential superplasticity can be obtained by adding to zinc-aluminum eutectoid alloys containing from 0.3 to percent by weight of copper, and from 0.01 to 0.1 percent by weight of magnesium, small amounts, of the order of from 0.005 to 0.3 percent by weight of at least one of the metals calcium, lithium and sodium. The alloys of the invention contain from 10 to 30 percent byweight of aluminum, the balance being zinc.

For most purposes preferred alloys of the invention contain to 24 percent by weight of aluminum, from about 0.75 to about 1.1 percent by weight of copper, from about 0.04 to about 0.05 percent by weight of magnesium, from about 0.01 to about 0.03 percent by weight of at least one of the metals calcium, lithium and sodium and the balance zinc.

The following are typical alloy compositions of the invention all parts being percent by weight:

TABLE I formed into useful products by any of the methods known in the art of forming superplastic alloys.

.The practical utilization of the alloys of the invention are not limited to uses involving superplasticity. Other applications of the alloys utilizing their excellent mechanical properties include such metal working techniques as forging (open die, closed die and precision) hot extrusion, impact extrusion, stamping, drawing and' screw machine techniques.

The results of tensile strength tests on typical alloys of the invention are given below. In the table the term hot-worked denotes the as-rolled or as-extruded material and the term heat-treated denotes the material that has been heat-treated between 275C. and 380C.

Comparative ultimate tensile strengths of an alloy consisting of 22 percent by weight of aluminum, 0.9 percent by weight of copper, 0.04 percent byweight of magnesium and balance zinc were 53,000 psi in the hot-worked state and 62,000 psi in the heat'treated I state.

copper, 0.01 to 0.1 percent by weight of magnesium,

0.005 to 0.3 percent by weight of at least one of the metals calcium, lithium-and sodium, and the balance zinc.

Al Mg Zn Balance Balance Balance Balance Balance 2. Zinc base alloys as defined in claim 1 consisting essentially of 20 to 24 percent by weight of aluminum, 0.75 to 1.1 percent of copper, 0.04 to 0.05 percent by weight of magnesium, 0.01 to 0.03 percent by weight of calcium and balance zinc.

3. Zinc base alloys as defined in claim 2 in which the calcium is replaced by lithium.

4. Zinc base alloys as defined in claim 2 in which the calcium is replaced by sodium. 

1. ZINC BASE ALLOYS HAVING IMPROVED MECHANICAL PROPERTIES CONSISTING ESSENTIALLY OF 20 TO 24 PERCENT BY WEIGHT OF ALUMINUM 0.3 TO 10 PERCENT BY WEIGHT OF COPPER, 0.01 TO 0.1 PERCENT BY WEIGHT OF MAGNESIUM, 0.005 TO 0.3 PERCENT BY WEIGHT OF AT LEAST ONE OF THE METALS CALCIUM, LITHIUM AND SODIUM AND THE BALANCE ZINC.
 2. Zinc base alloys as defined in claim 1 consisting essentially of 20 to 24 percent by weight of aluminum, 0.75 to 1.1 percent of copper, 0.04 to 0.05 percent by weight of magnesium, 0.01 to 0.03 percent by weight of calcium and balance zinc.
 3. Zinc base alloys as defined in claim 2 in which the calcium is replaced by lithium.
 4. Zinc base alloys as defined in claim 2 in which the calcium is replaced by sodium. 